Technical Field
The present disclosure relates generally to plasmonics, and more specifically to electronic-plasmonic devices
Background Information
Optical circuit components can carry information with a capacity exceeding 1000 times that of electronic circuit components. However, the relatively large wavelength of light requires optical components to be too large to compete in size with the nanoelectronics used in modern high-speed integrated circuits (“chips”). To address this issue, there has been growing research into the use of plasmons, surface plasmon polaritons (SPPs) to create a hybrid of optics and electronics, which can take advantage of the small dimensions of nanoelectronics and the fast operating speed of optics. SPPs are infrared or visible-frequency electromagnetic waves, which travel along a metal-dielectric or metal-air interface. The waves involve both charge motion in the metal (“surface plasmons”) and electromagnetic waves in the air or dielectric (“polaritons”). SSPs can be confined to sub-wavelength dimensions and can carry information at high speeds (e.g., >100 terahertz THz).
To this end, there is a need for circuit components that can excite and detect plasmons (i.e. electronic-plasmonic transducers). However, existing approaches for plasmon excitation and detection suffer a number of shortcomings that render them unsuitable for use in high-speed integrated circuits. Most existing approaches for on-chip plasmon excitation or detection are based on miniaturized semiconductors. The use of miniaturized semiconductors entails the extra step of electron-hole pair generation in the semiconductor, such that plasmon excitation or detection is indirect. The inefficiency of this extra step generally renders the devices unsuitable for high-speed applications.
There have been some attempts to directly generate plasmatic signals. However, the electron-to-photon conversion efficiencies achieved have been very low (e.g., only one photon generated per 104-107 electrons), thereby rendering them unsuitable for use in practical applications. There have also been some separate attempts at the reverse process of modulating current flow directly in response to plasmonic signals. Again, however, the efficiencies achieved (here photon-to-electron conversion efficiencies) have been very low. Further, the attempts at direct plasmon generation and direct plasmon detection have involved different structures, such that the capabilities of generation and detection have not been both present in the same structure. An on-chip structure capable of both plasmon generation and detection by directed electrical means has yet to be demonstrated, much less one that achieves practical efficiencies suitable for high-speed integrated circuits.
Accordingly, there is a need for a new on-chip electronic-plasmonic transducer that can both directly generate and detect plasmons with high efficiencies.